1. Field of the Invention
The present document relates to a flexible substrate. More particularly, the present document relates to a flexible substrate for a display apparatus.
2. Description of the Related Art
A flexible substrate is used to reduce the cost price and the workability of display apparatuses such as a Liquid Crystal Display (LCD), a Plasma Display Panel (PDP) and an Organic Electro Luminescent Display (OELD). For example, if a Tape Carrier Package (TCP) (i.e., one of the flexible substrates) is used as the package of the data driver Integrated Circuit (IC) chip of the display apparatus, the cost of the package itself can be saved and there are several advantages in terms of the process since the package supply and attachment processes can be automated.
The flexible substrate includes a Chip on Film (COF) and a TCP in which an IC chip is packaged, and a Flexible Printed Circuit (FPC) in which a circuit is simply patterned.
FIG. 1 is a drawing illustrating a display apparatus in the related art.
FIG. 1 shows an example of a flexible substrate used for a plasma display apparatus of the display apparatuses. As shown in FIG. 1, the plasma display apparatus has a control board 20, a data driving board 21, a flexible substrate 23, a plasma display panel 22 and a scan/sustain driving board 24. Each of the boards 20, 21 and 24 is directly grounded (GND) to a heat sink plate (not shown) formed on a rear side of the plasma display panel 22. There occurs a difference in the impedance between the grounds (GND) of the boards 20, 21 and 24 because of several causes.
Meanwhile, the flexible substrate 23 has a ground structure connected to the heat sink plate through the data driving board 21. Accordingly, problems arise because the flexible substrate 23 is influenced by pulses supplied from the driving boards 21 and 24 to the plasma display panel 22 and is vulnerable to electromagnetic interference. In other words, there are problems in that noise is generated in the pulses supplied through the flexible substrate and in even worse conditions, IC chips formed in the flexible substrate are failed.